1. Field of the Invention
The present invention relates to a cell for measuring the ability of a chemical substance to control the activity of a ligand-responsive transcription control factor.
2. Description of the Related Art
A ligand-responsive transcription control factor is a protein functioning to promote transcription of a target gene on a DNA, such as a chromosome, in which said protein binds to a respective ligand to be activated and binds to a ligand-responsive transcription control factor recognizing sequence present in a transcription control region of said target gene. As such, the ligand-responsive transcription control factor plays important roles in maintaining homeostasis, reproduction, development and growth, cell differentiation, energy metabolism, drug metabolism and the like of organisms. It is known that when the transcription control by such a ligand-responsive transcription control factor is not normal, an abnormality occurs in the transcription activity of the target gene of said factor, causing various diseases and abnormalities.
In order to develop drugs useful for preventing and treating such diseases and abnormalities, there have been attempts searching for chemical substances having an activity to change the transcription control ability of a ligand-responsive transcription control factor. Further, there has been desired the development of efficient methods to investigate the activity of chemical substances over the transcription control ability of said ligand-responsive transcription control factor.
Nonetheless, it has been recently reported that some chemical substances in the environment show the action of a chemical substance in connection with the transcription control ability of a ligand-responsive transcription control factor, such as an allylhydrocarbon-like action or anti-allylhydrocarbon-like action, intranuclear hormone-like action or anti-intranuclear hormone-like action, estrogen-like action or anti-estrogen-like action, androgen-like action or anti-androgen-like action, thyroid hormone-like action or anti-thyroid hormone-like action, and the like (hereinafter, referred to as the present ligand-responsive transcription control action). Since there is a fear that such actions of chemical substances collapse the hormone balance in animals, disorder an ecosystem or cause diseases, there are attempts to measure the present ligand-responsive transcription control action of a chemical substance as a part in safety evaluations of a chemical substance.
In the case of estrogen for example, the action mechanism thereof may be as follows: when estrogen binds to an estrogen receptor present in the target cell of estrogen, such a receptor is activated, binds to an estrogen receptor-recognizing sequence present in a transcription control region of the target gene on the DNA, such as a chromosome, and promotes the transcription of the target gene. In this regard, there has been desired the development of test systems which can measure the ability of a chemical substance to control the estrogen receptor activity, as a method to measure the estrogen-like action or anti-estrogen-like action of a chemical substance.
Further, in the case of androgen for example, the action mechanism thereof may be as follows: when androgen binds to an androgen receptor present in the target cell of androgen, such an receptor is activated, binds to an androgen receptor-recognizing sequence present in a transcription control region of the target gene on a DNA, such as a chromosome, and promotes the transcription of the target gene. In this regard, there has been desired the development of test systems which can measure the ability of a chemical substance to control the androgen receptor activity, as a method to measure the androgen-like action or anti-androgen-like action of a chemical substance.
Furthermore, in the case of thyroid hormone for example, the action mechanism thereof may be as follows: when thyroid hormone binds to an thyroid hormone receptor present in the target cell of thyroid hormone, this receptor is activated, binds to a thyroid hormone receptor-recognizing sequence present in a transcription control region of the target gene on a DNA, such as a chromosome and promotes the transcription of the target gene. In this regard, there has been desired development of test systems which can measure the ability of a chemical substance to control the thyroid hormone receptor activity, as a method to measure the thyroid hormone-like action or anti-thyroid hormone-like action of a chemical substance.